Flexographic Printing Blog

10 Common Causes of Print Misregistration in Flexographic Printing

Print registration is the precise alignment of your ink combinations on the substrate. Misregistration by the tiniest fraction of an inch can completely skew your print.

Misregistration impacts everything from color patterns to design accuracy. It also means downtime for troubleshooting. For you, that means:

Wasted time

Wasted substrate

Wasted ink

Unnecessary wear and tear on machinery

Delays in getting prints to the customer

All of that means wasted money. Here are the most common causes of print misregistration.

10 Common Causes of Print Misregistration

1. Inaccurate Plate Mounting/Centering

Whether using cameras, mirrors, or the naked eye, the exact centerline of the printing cylinder, plate, or sleeve should be identified. The cylinder or sleeve must be mounted in the same location and orientation.

2. Impression Cylinder Concentricity

Your cylinder’s concentricity (a tolerance zone for the median points of a cylindrical or spherical part) must be close to perfect as possible. A dial indicator capable of showing errors down to 0.0001 inches should be mounted on a magnetic base and used to produce measurements from the middle and near each end of the cylinder.

Generally accepted flexo printing guidelines say total concentricity run out shouldn’t be more than about 0.0005 inches.

4. Gear Condition

Missing gear teeth and general gear misalignment can create print misregistration issues. Make sure all gears are intact and positioned properly. The plate cylinder gear must fit the cylinder journal with a tolerance no greater than 0.002 inches of error.

Also make sure the gears are clear of excess grease and foreign materials.

5. Idle Rollers Drag or Rotate Irregularly

Dragging or wobbly rotation makes accurate ink transfer impossible. Your inked image carrier will not be making contact with the substrate at the proper time and place.

6. Malfunctioning Web Guide

The web guide is a closed-loop system, which includes:

Sensor

Controller

Actuating cylinder

Web

The sensor gives error signals to the controller to adjust velocity differential across the web. Correct sensor prepositioning is critical.

7. Web Growth or Fanning Out

The web width gradually grows as it travels from one station to the next, causing print misregistration as images are applied in layers. You can use prepress software or bustle wheels to compensate for the growth.

8. Wandering Web

Any lateral movement of your web will cause print misregistration. Manipulate the tension at the splicer to hold your substrate steady.

9. Substrate Surface Tension

If surface tension is off, it will not correctly absorb and distribute pressure to transfer ink from the image carrier. Keep tension at an appropriate level so the image carrier contacts the substrate evenly and uniformly.

10. Incorrect Tolerances

Register shifts can cause two letters, words, or designs printed next to each other to overlap or misalign. Make sure images with different colors are more than twice the image trap dimension from each other.

Avoid Issues Leading to Poor Flexographic Print Registration

Much can go wrong on a printing press, but making sure mechanical components and pre-press calibrations are correct will avoid costly print misregistration errors.